An erythroid cell-specific transcription factor, EKLF (erythroid Kruppel- like factor), has recently been isolated and characterized. EKLF is very important for the development of erythroid cells. Preliminary studies indicate that, in mouse bone marrow 32D cells, the EKLF message can be induced to high amounts at the transcription level by erythropoietin (EPO), a hormone regulating differentiation and proliferation of erythroid progenitor cells and the level of circulating blood cells. In addition, the genomic clone of EKLF has been isolated. Based on these studies, I propose to investigate the mechanism of induction of EKLF by EPO. The EPO response element and its binding protein(s) will be identified. Details of how this protein(s) is involved in the transduction of the extracellular EPO signal also will be determined. These studies will illuminate how erythroid cell specific production of an intracellular regulatory molecule is accomplished and is related to signals from extracellular EPO.